Abstract:

The rare and endangered plant, Ammopiptanthus nanus is the only evergreen broad leaved plant in Xinjiang listed as a Category 1 National Protected Plant. It is a xerophytic relict species of the subtropical evergreen forests of the Tertiary and found only in the arid Tarim Basin. Previous studies have examined the anatomical characteristics and drought-resistant mechanisms of this species. In this paper, we examined seed characteristics, including germination in relation to temperature and various light regimes duration of storage, seedling emergence and survival rate in relation to soil moisture content (MC) and seeding soil depth, and effects of a fungicide treatment. Our results showed that Ammopiptanthus nanus seeds were dispersed only short distance from the parent plants due to their morphological characteristics and high predation rates. the seed germination rate reached 38% in seeds stored for 60 d at ambient temperature (AT) of 18 - 32 ℃. The dried and ripened seeds of this plant often had impermeable seed-coats, and only 33.33% of the dried seeds with 7.68% MC absorbed water and swelled up after soaking for 90 h at 30 ℃. Seed germination did not require illumination. Germination percentage (GP) was above 80% when seeds were incubated for 9 d at 15 ℃, 20 ℃, 25 ℃ , 30 ℃, 20/30 ℃ and AT, and seeds germinated most quickly at 30 ℃. The seedling emergence rates were greater than 75% when seeds were buried in 1-2 cm depth below the surface of sandy soil. Seedling emergence rates decreased with increasing soil depth and were less than 20% at 6 cm soil depth. The most suitable MC of sandy soil for seedling emergence was 19.35%-28.75%; when soil MC was above 32.43% or below 3.85%, few seedlings emerged. After seed storage for 210 d at 10 ℃ and　5 ℃, MC of 19.36%, 10.64% and 7.68% had no significant effect on GP, but GP decreased significantly at AT and 35 ℃. The decreasing GP rate had a significantly positive correlation with seed MC or storing temperature. When sowing seeds and nursing seedlings in soils of 7.41%, 13.79% and 28.75% MC, the seedling mortality rates were 77.49%, 81.25% and 89.49% respectively. When seeds were treated with triadimefon, mortality rates were still as high as 50.27%, 69.53% and 76.03% in the three soil MC treatments, respectively. The seedling mortality rate had significant positive correlation with sandy soil MC.